Advertising can occur in any of various different contexts. For example, ads are commonly included in: printed media such as newspapers and magazines; broadcast media such as radio and television content; and online media such as individual pages, portals and streamed content. Some advertising is done based on a “conversion”-type compensation model. In some online media, an advertiser who successfully bids on the placement of a particular ad agrees to pay an advertising fee for every user who clicks on (or otherwise activates) the ad and completes a predefined operation, for example purchasing a product or service, or establishing an account.
Ads are sometimes selected based on an ad prediction model. An ad serving organization may have a repository of hundreds of thousands of ads or more that are candidates for being served, and the organization uses the model to make a prediction about the effectiveness for individual ads. For example, the ad prediction model can be used to determine a predicted click-through rate for serving a particular ad on a page presented to a specific user.